The present invention relates to a device for controlling an opto-electronic display device which has dot-matrix-display elements, a controller including an addressable dot-matrix character table with a program-control device as character generator, and at least one driver of the display elements.
The invention, furthermore, relates to a method of controlling such as opto-electronic disiplay device.
Alpha-numeric characters can be reproduced in dot-matrix or segment display. Both methods of display have basic advantages, depending on the nature of the alpha-numeric characters to be represented, legibility and other criteria. Therefore, it may be desirable to display a first group of data, referred to hereinbelow as input data, by a dot-matrix display, and a second group of data (input data) by a segment display. For example, the first group of input data may contain date information, such as the days of the week, while the second group of data may contain time information, such as the hour of the day.
Liquid-crystal display elements are particularly suitable for display in segment representation. However, vacuum fluorescence display elements and other opto-electronic display elements also enter into consideration.
In one known device of the aforementioned type for controlling an opto-electronic display device with dot-matrix display elements, an essential element is a controller which comprises a character generator as well as a driver which acts on the display elements. The character generator contains specifically a character table in which the set of characters to be displayed is stored in addressable fashion. In the character table in which the characters to be shown in dot-matrix display elements are stored, each storage place contains one matrix dot of the character to be displayed. Corresponding to the input data which are coded for the addressing of the character table the dot-matrix data are read out of the character table, controlled by a program control for each character to be shown and fed via the driver to the dot-matrix display elements. The dot-matrix display elements can be controlled for a 5.times.7 dot matrix with a multiple rate of 1:7 in time-division mode. For the display of characters by the segment display elements, on the other hand, a different method of control is used in the prior art: For this purpose, the input data, which in the present case are the input data of the second group are so re-coded by a program that the segments for each dot-matrix display element are controlled in a manner corresponding to the alpha-numeric characters to be displayed. In this connection, the dot-matrix display elements may be acted on by a driver in time-division mode, to which there ordinarily corresponds a multiplex rate of 1:3, since one back electrode can be associated with three front electrodes. Upon re-coding of the input data, therefore, the program must be able to convert the entire set of alpha-numeric characters into a large number of segment data which are to be transferred into the controller, i.e. the driver. If, therefore, it is desired to use dot-matrix and segment representations alongside of each other, then the formation of the segment data and the formation of the matrix-dot data from the input data are effected in fundamentally different ways. This results in a high expense as well as in additional operating disadvantages, particularly in connection with the transfer of the re-coded data. The ordinarily different multiplex rates with which dot-matrix display elements and segment display elements are operated have the disturbing result, visible from the outside, that the two displays are of different contrast.